A Method for Determining the Length of FBG Sensors Accurately

Rajabzadeh, Aydin; Heusdens, Richard; Hendriks, Richard C.; Groves, Roger M.

doi:10.1109/lpt.2019.2891009

Cited by 2 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2b that the retrieved length of the sensor in this example is L = f max /(2n eff ) = 7.8892 mm. 8 In the first instance of locally heating the FBG via wire 1, the emerging harmonics are at f 1 = 0.005336 m and f 1 = 0.0177 m. Note the symmetry of the location of the new harmonics with respect to the central frequency in the Fourier domain at f c = f max /2 = 0.0114 m. From this first measurement, it can be deducted that wire 1 is either at…”

Section: Methodsmentioning

confidence: 85%

“…Here, λ is the wavelength region under interrogation, λ i is the local Bragg wavelength of the i'th segment, and n eff is the effective mode index of the core. In our previous work 8 we showed that there is a linear relationship between the active gauge length of the FBG (even under extremely non-uniform stress fields) and the maximum harmonic frequency of (1). We used this to accurately calculate the active gauge length of the FBG sensor.…”

Section: Problem Formulationmentioning

confidence: 95%

“…refers to the reflection spectrum under a smooth strain field, and R r is the summation of all remaining terms from the expansion (with lower amplitudes than the other terms in ( 5)). 8 Note that the information regarding the length of the sensor is in R s , as the oscillating term in R s is cos(2π2M ∆zn eff (1/λ − 1/ λ)), which linearly depends on L = M ∆z. In fact, this term has the highest oscillation frequency among all the harmonics presented in (5), with a value of f max = 2Ln eff , from which the exact length of the sensor can be retrieved.…”

Section: Problem Formulationmentioning

confidence: 99%

“…In fact, this term has the highest oscillation frequency among all the harmonics presented in (5), with a value of f max = 2Ln eff , from which the exact length of the sensor can be retrieved. 8 As seen from ( 5), for a single excitation of the FBG at segment t, two new harmonics will emerge in the reflection spectrum with angular frequencies ω = 2M − 2t and one at ω = 2t. This means that with a single excitation, one cannot determine the exact location of the excitation, as there will be a reflection line of symmetry ambiguity in localising the excitation.…”

Section: Problem Formulationmentioning

confidence: 99%

“…The ambiguity of the excitation point is thus resolved. Moreover, the exact length of the sensor can be retrieved using the method presented in, 8 which determines the overall number of segments M in the FBG model. With the knowledge of the accurate length of the sensor, and the exact excitation segment, the precise start and end point of the sensor can be determined.…”

Section: Problem Formulationmentioning

confidence: 99%

See 4 more Smart Citations

A method for determining the position of FBG sensors accurately

Rajabzadeh

Hendriks

Heusdens

et al. 2019

Seventh European Workshop on Optical Fibre Sensors

Self Cite

View full text Add to dashboard Cite

Fibre Bragg grating sensors have gained a lot of attention in damage detection and strain measurement applications in the past few decades. These applications include matrix crack detection and delamination tip monitoring in composite structures, crack detection in concrete and civil engineering structures and etc. The damage localisation accuracy of such methods, directly depends on precise knowledge on the position of the FBG sensor. However, this information is not commonly provided by manufacturing companies with such accuracy. In this paper, we propose a novel approach to accurately determine the position of an FBG sensor with a low complexity setup. The proposed method offers an accuracy of below 10 µm, and can consequently increase the spatial resolution of damage detection methods.

show abstract

Section: Methodsmentioning

confidence: 85%

Section: Problem Formulationmentioning

confidence: 95%

Section: Problem Formulationmentioning

confidence: 99%

Section: Problem Formulationmentioning

confidence: 99%

Section: Problem Formulationmentioning

confidence: 99%

See 3 more Smart Citations

A method for determining the position of FBG sensors accurately

Rajabzadeh

Hendriks

Heusdens

et al. 2019

Seventh European Workshop on Optical Fibre Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

Load monitoring of a cantilever plate by a novel multimodal fibre optic sensing configuration

Nazeer

Groves

2021

SN Appl. Sci.

Self Cite

View full text Add to dashboard Cite

Optical fibre sensors and in particular fibre Bragg gratings (FBG) have received a lot of interest for Structural Health Monitoring in different application fields, such as aerospace, pipeline and civil engineering. FBGs are conventionally used to monitor strain and sometimes temperature. In this paper, we propose a new method for load monitoring of a cantilever plate subjected to point loading. The bending of plate is complex due to the interaction between the axial and transverse bending stiffnesses of the material. We use a novel algorithm for interrogating fibre Bragg grating sensors based on both hybrid interferometry and FBG spectral sensing. The method is demonstrated in this paper using a single-mode optical fibre containing four FBG sensors to estimate both the point loading position and the loading magnitude at an arbitrary location on a 1 m$$^{2}$$ 2 cantilever plate. The algorithm first utilizes point strain information through spectral sensing as well as strain from interferometric sensing over a long path. The gratings are interrogated using Wavelength Division Multiplexing (WDM). We calibrated the system using an experimental model. This model was then verified by using single point static loading tests and comparing the calculated sensing position with the actual position. The method achieved a good estimation of loading position achieving a measurement error of about 9% in a 2D plane. The analysis discusses the possible sources of inaccuracies. This study forms the basis of our future work involving morphing smart-wing sections for the purpose of load monitoring. Article highlights A new optical sensing configuration is demonstrated for load and structural health monitoring of cantilever structures. The algorithm successfully estimates the position of an arbitrary load on a cantilever plate, with an error of 9%. This methodology will be extended to monitor more complex structures, in- cluding morphing aircraft wing sections.

show abstract

A Method for Determining the Length of FBG Sensors Accurately

Cited by 2 publications

References 8 publications

A method for determining the position of FBG sensors accurately

A method for determining the position of FBG sensors accurately

Load monitoring of a cantilever plate by a novel multimodal fibre optic sensing configuration

Contact Info

Product

Resources

About